1. Field of the Invention
This invention relates to storage control technology.
2. Description of the Related Art
Technology related to storage systems includes the disclosures in Japanese Patent Laid-open No. 2001-256003, Japanese Patent Laid-open No. 2003-140837, Japanese Patent Laid-open No. 8-328760, Japanese Patent Laid-open No. 10-63576, and Japanese Patent Laid-open No. 2002-123479.
Architecture which can be applied to storage systems includes, for example, a common memory architecture, and a distributed memory architecture.
According to a common memory architecture, various information related to the storage system is stored in common memory, and any interface board within the storage system (for example, an interface board to a host device, or an interface board to a media drive), can access the information in the common memory. However, as a consequence there is a concentration of accessing of the common memory, resulting in a bottleneck.
According to a distributed memory architecture, there exist a higher-level router/switch portion, which has routing and switching functions, and a plurality of lower-level modules divided in a RAID configuration. The higher-level router/switch portion receives commands from host devices, analyzes the commands, judges which of the plurality of modules should be accessed, and can access one or more modules among the plurality of modules. However, as a result the load on the router/switch portion becomes excessive. Also, because a single RAID configuration is provided through a plurality of modules, when a malfunction occurs in one module, the RAID configuration is disrupted even if the other modules operate normally.
Hence one object of the invention is to provide novel storage control technology which resolves the problems of both common memory architectures and distributed memory architectures.
Other objects of the invention will become clear from the ensuing explanation.